because this photo looks exactly like a postcard from the 1920s, that my father bought when he climbed the Grossglockner in 1927. Of course the postcard was in black and white (though very sharp), but even the shape and size of the summit cornice is the same

Thanks Lodewijk
When we left the Studlhutte it was still raining and covered in cloud. Everything cleared when we got to the Erz Johann hut and we got amazing views over the Kleinglockner and Grossglockner. As we descended the cloud came back over, so our timing was perfect. We were so lucky!